1. Field of the Invention
The present invention relates to systems and apparatus for protecting vehicle occupants from injury. More specifically, the present invention relates to an airbag module that is designed to reduce the leakage of inflation gases during inflation of the airbag cushion.
2. Description of Related Art
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. Additionally, airbags may be installed to inflate beside the passenger to provide side impact protection, in front of the knees to protect the knees from impact, or at other strategic locations.
In the event of an accident, a sensor system within the vehicle senses an impact situation and triggers the ignition of an inflator. Inflation gases from the inflator fill one or more airbag cushions, which immediately inflate to protect the driver and/or passengers from impact against the interior surfaces of the vehicle. During normal vehicle operation, airbags are typically stowed behind covers to protect them from tampering and provide a more attractive interior facade for the vehicle.
One type of known airbag module includes a diffuser that is positioned inside the airbag cushion. A typical diffuser includes a diffuser panel that includes a plurality of venting apertures. A single layer of the airbag cushion is spread across the top side of the diffuser panel, while the remainder of the airbag cushion is folded underneath the diffuser panel. The inflator is typically attached to the diffuser. When the inflator discharges, the inflation gases released by the inflator travel through the venting apertures in the diffuser panel, thereby increasing the pressure in that region and effectively “pushing” the layer that is spread over the top side of the diffuser panel away from the diffuser panel. Such movement of the top layer of the airbag cushion causes the rest of the airbag cushion to be “pulled” out of the diffuser and into its inflated position.
An airbag module that employs a diffuser in the manner described possesses several advantages over other types of airbag modules. For example, the airbag cushion generally possesses a larger surface area while it is inflating than in other designs. In addition, the amount of breakout force that is required is generally less than in other designs.
Unfortunately, however, known airbag modules that include a diffuser are typically prone to leakage of inflation gases. Such leakage generally occurs at the point of attachment between the inflator and the diffuser, although leakage may also occur through other similar attachment joints. Accordingly, benefits may be realized by an airbag module that includes a diffuser, as described, but that is designed to reduce the amount of leakage that occurs during inflation of the airbag cushion.